<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
            margin:0;
        }
        .head{
            width: 7.5rem;
            height: 1rem;
            background-color: red;
        }
        .nav{
            width:3.75rem;
            height:1rem;
            background-color: yellow;
        }
    </style>
</head>
<body>
    <div class="head">

    </div>
    <div class="nav"></div>
    <script src="autosize.js"></script>
</body>
</html>